There's one thing I never got in Star Wars. The first Death Star was destroyed because there was a small ventilation shaft that lead to the core of the station and which would let only a small projectile through. So why would the Imperials rebuild it with a bigger ventilation shaft to allow ships to fly into it? It makes no sense, did they not learn the first time round?

And why did they not have better shields? OK, they did have a shield but it had to be generated from down on a planet. If I had given the location of the base to rebels to get them to come into a trap I would at least build a shield generator so if the planet one failed, which they thought it might, I would have a back up. So why didn't they have a second shield generator?

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    They were stupid? They were so convinced of their own invulnerability that they didn't bother to take precautions? If you don't believe the ship can sink, you don't bother too much about lifeboats. Mar 7, 2012 at 10:06
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    well they needed the ventalation shaft. And since a small one proved dangerous the only other choice is a large one... sounds like sound logic of a bureaucrat to me
    – Chad
    Mar 7, 2012 at 14:06
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    I like how the title is capitalized. It's like the ventilation is "one bad mother- " "shut your mouth!"
    – KSmarts
    Feb 17, 2015 at 22:57
  • It was in space, why do they need ventilation?
    – Danny Mc G
    Apr 24, 2020 at 6:45

6 Answers 6


The second Death Star was in the process of being built; you cannot assume just because they could attack it by flying inside it to attack its reactor core that this means that they were building a 'bigger ventilation shaft' that would allow it to be attacked like that when completed.

The Endor-generated shield was a level of power above any shields we have seen in Star Wars. It was able to prevent any ship from approaching the Death Star - whereas the original appeared to have little or no shields, and relied on its other defenses. It had been designed to defend against capital ships approaching it and the rebels attacked with ships that were too small.

The fact that the shield generator was so powerful shows that the Empire had learnt from the original, and it's not entirely surprising to think that a shield generator to protect something of that size might require more power than the partially built Death Star could provide.

I do not think that we can see any oversight in the Death Star II design just because of the events in RotJ.

  • Correct me if I am wrong but do they not point out a ventilation shaft in the plans when they plan the attack. Are was it just an opening?
    – Popeye
    Mar 7, 2012 at 13:08
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    I do not recall (but you are probably right) - but that does not mean that the shaft would be open and unshielded in the completed station. I am an Engineer, and the last design mistake we make nearly always is fixed in the next one. The hard part of the job is anticipating the next one :-) Mar 7, 2012 at 13:11
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    Yes and they needed to move on the deathstar now as that secition with the opening would be completed soon eliminating the vulnerability.
    – Chad
    Mar 7, 2012 at 14:08

I don't see a problem here. The second Death Star was not yet completed (while the first one was). You could see the huge holes from far away.

  • Yes - the real issue is why you would build the thing over an uncontrolled planet, rather than at a dockyard where you actually have men and material that you can use to finish it available.
    – Oldcat
    Dec 20, 2014 at 0:04
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    @Oldcat - Because they want to keep it a secret, and they do have a sizable chunk of the fleet to secure it? Feb 17, 2015 at 21:15
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    @iandotkelly Or because they wanted the rebellion to think that it was a secret, when they actually had a sizable chunk of the fleet to secure it. I think Admiral Ackbar had something to say about the situation...
    – KSmarts
    Feb 17, 2015 at 22:59
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    @Oldcat because IT'(wa)S A TRAP!
    – Petersaber
    Feb 22, 2018 at 18:17

The Empire did learn after the first go around. However, the second Death Star was unfinished and the Rebels were able to infiltrate it by flying into the unfinished super-structure.

From the script:


Rebel fighters follow the Falcon across the surface of the Death Star to the unfinished portion, where they dive into the super-structure of the giant battle station, followed by many TIE fighters.

WEDGE I'm going in.

LANDO Here goes nothing.

Three X-wings lead the chase through the ever-narrowing shaft, followed by the Falcon and four other fighters, plus TIE fighters who continually fire at the Rebels. Lights reflect off the pilot's faces as they race through the dark shaft.

According to the Essential Guide to Vehicles and Vessels (1996):

Not only was the second Death Star larger and more deadly, but several flaws in the original design were corrected. The vulnerable thermal exhaust ports were replaced with millimeter-wide heat dispersion ducts, leaving no weak spots in this battle station's armor.


This new Death Star would have been invincible; the only way to stop it would have been to destroy it while it was still under construction.


A small team of Rebel commandos was able to enlist the Ewoks' aid and destroy the shield generator, thus allowing the Millennium Falcon, commanded by General Lando Calrissian, to fly inside the partially completed battle station and destroy its power core.

  • They were so smart to build the ship from left to right!
    – Oldcat
    Jul 31, 2014 at 23:41


IT'S A TRAP! - Admiral Ackbar

The emperor is in charge, and he wants to capture Luke and destroy the Rebellion, so he sets up a trap with the new Death Star as bait, but offering what looks like an opportunity to destroy the new Death Star before it is completed, but not making it look too easy, nor too difficult.

The second "shaft" isn't a bigger ventilation shaft, but a winding path through the unfinished structure of the base to the reactor core, which would only be possible to get to if you knew about it by heroically sacrificing (Bothan, in this case) spies to gather the plans of the base and its shield.

The emperor makes this general strategy pretty clear when he gloats to Luke about how the station is fully-operational, the shield will stay up, and his friends will die. This disappointment was evidently also part of his plan to get Luke emotional enough to turn to the Dark Side.

If they had redundant shields and/or no possible way to destroy the Death Star, the Rebels would not likely not have come to the trap at all.

However even despite all that, I think you have a good point. In particular, since flying through the station takes a long and narrow path, it seems to me they could have arranged to block it somehow. Drop a slab over the tunnel path once the Rebels fly into it. All I can imagine for that, is that maybe the Emperor realized any defense plan which could make an attack impossible, could be intuitively sensed by Luke or Yoda. Or it might be discovered by those spies that were part of the plan, revealing the whole setup as a trap.


The temperature and pressure of gas in a small exhaust pipe will be much greater than those of a larger exhaust pipe conveying the same material. This greater temperature and pressure would make a small exhaust pipe much more susceptible to certain forms of catastrophic cascading failure than a large one would be. The walls of a small exhaust pipe will need to be able to withstand great heat and pressure, but the material near the walls might not be so tough. If a breach in the pipe exposes the support structures to gases which have enough energy to melt them, the failure of those support structures may cause further failures in the pipe, leading to the chain reaction seen in the first movie.

Increasing the cross sectional area of the exhaust pipe would greatly reduce the temperature and pressure of the exhaust carried nearby, quite possibly to the point that it would pose no immediate threat to the alloys used for general-purpose station construction. Such a design change would eliminate the possibility of a chain reaction of the type that destroyed the first Death Star, and would mean that the reactor would only be vulnerable to something that could actually fly all the way to it. Guarding against that threat was perceived as being much easier than guarding against the possibility of the rebels getting photon torpedo a few feet into an exhaust pipe. As to whether more defensive measures for the shaft should have been built sooner, putting more attention on those areas would have meant that other areas of the station received less attention, possibly leaving vulnerabilities there.


This is addressed (canonically) in the new junior novelisation for Return of the Jedi. In short, the Falcon has slipped through a 'crack in the armor' of what was going to be an extraordinarily well-armoured space station. It was the Emperor's hubris that resulted in it being exposed (as bait) to the Rebellion before the quadanium steel shell was completed.

Though unfinished, this Death Star was going to have some improvements over the last one. You may recall that a ventilation shaft that led straight to the main reactor doomed that one. The ventilation shafts are still there—we just saw the Emperor fall down one, after all—but this time Jerjerrod made sure the exhaust ports were very, very, very heavily armored. In the plans, at least.

And, had the Emperor allowed Jerjerrod more time—not to mention more money and more workers—the whole thing would have been shut up tight.1

But an unfinished Death Star was part of the bait for the Emperor’s trap…and now it’s providing just enough room for the fighters and the Falcon to slip through a crack in the armor and shoot straight for the heart of the space station, the reactor core.

Return of the Jedi: Beware the Power of the Dark Side!

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